Abstract
For all species, finite metabolic resources must be allocated toward three competing systems: maintenance, reproduction, and growth. Telomeres, the nucleoprotein tips of chromosomes, which shorten with age in most species, are correlated with increased survival. Chick growth is energetically costly and is associated with telomere shortening in most species. To assess the change in telomeres in penguin chicks, we quantified change in telomere length of wild known-age Magellanic penguin (Spheniscus magellanicus) chicks every 15 days during the species’ growth period, from hatching to 60 days-of-age. Magellanic penguins continue to grow after fledging so we also sampled a set of 1-year-old juvenile penguins, and adults aged 5 years. Telomeres were significantly shorter on day 15 than on hatch day but returned to their initial length by 30 days old and remained at that length through 60 days of age. The length of telomeres of newly hatched chicks, chicks aged 30, 45 and 60 days, juveniles, and adults aged 5 years were similar. Chicks that fledged and those that died had similar telomere lengths. We show that while telomeres shorten during growth, Magellanic penguins elongate telomeres to their length at hatch, which may increase adult life span and reproductive opportunities.
Highlights
In all species, finite metabolic resources must be allocated toward three competing systems: survival, reproduction, and growth [1, 2]
We show that while telomeres shorten during growth, Magellanic penguins elongate telomeres to their length at hatch, which may increase adult life span and reproductive opportunities
By 30 days of age, telomere length was similar to their length at hatching, and they remained unchanged through 60 days of age (p=0.002, n=65, TukeyHSD, Figure 1)
Summary
Finite metabolic resources must be allocated toward three competing systems: survival (or maintenance), reproduction, and growth [1, 2]. With a decreased annual survival rate; resource investment should favor growth and reproductive, rather than maintenance systems. While long-lived species will still incur the resource bias during growth, they should allocate resources to systems that benefit increased longevity. Evidence of this tradeoff is known, as developmental conditions like brood size [9], growth rate [10] and being smaller than brood-mates [11] are shown to affect survival [12, 13]. We hypothesize that the continual investment cost in maintenance systems, like telomeres, increases the potential of adult survival and future reproductive events
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